Terminal electrode forming method in chip-style electronic component and apparatus therefor

ABSTRACT

The invention provides an electrode forming method with steps of arraying chip-style electronic components on an arraying flat bed thereby positioning and aligning the components, lowering a film coated with an adhesive in relative manner together with an adhering top plate parallel to the arraying flat bed thereby adhering ends of the positioned and aligned chip-style electronic components to the adhesive, then lowering the first film to which the chip-style electronic components are adhered in relative manner together with a coating top plate parallel to a coating flat bed provided with a conductive paste layer of a constant thickness thereby pressing the other ends of the chip-style electronic components to the coating flat bed and coating the ends of the electronic components with the conductive paste.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a terminal electrode formingmethod for a chip-style electronic component and an apparatus therefor,and more particularly to a terminal electrode forming method for achip-style electronic component and an apparatus therefor, capable ofadapting to miniaturization of the chip-style electronic component,improving the quality of the terminal electrode and adaptable to massproduction by executing conductive paste coating etc. while holding thechip-style electronic component by a film coated with an adhesivematerial.

[0003] 2. Related Background Art

[0004] In general, the terminal electrode formation in a chip-styleelectronic component means forming a connecting electrode at an end ofthe chip-style electronic component by coating, drying and sinteringpaste containing silver, silver-palladium, copper etc. on such endportion, for the purpose of connection with an internal conductor or aninternal electrode of the chip-style electronic component. The presentinvention describes a method for forming a terminal electrode on bothends of a chip-style electronic component such as a ceramic capacitor ora noise filter.

[0005] In the conventional terminal electrode forming method for thechip-style electronic component, the chip-style electronic componentsare held, as shown in FIG. 11, by forming holding holes 51 in siliconerubber 60 and inserting the chip-style electronic components 1, alignedby an insertion guide plate 52, into the holes 51 with inserting pins53. Such holding method for the chip-style electronic components ishowever associated with the following drawbacks.

[0006]FIGS. 12 and 13 show a state in which the chip-style electroniccomponents 1, inserted and held in the holding holes 51 shown in FIG.11, are positioned downwards for conductive paste coating, and, in suchstate, the chip-style electronic components 1 are supported by theelasticity and friction of rubber 50. Thus, at the insertion, thechip-style electronic components are inserted by sliding into the holes51 of the rubber 50, and, at the holding, they are supported by theelasticity of rubber 50 and the friction of the contact portions. Thus,the chip-style electronic component may not be properly placed at thedesired position because sliding and friction, which are mutuallycontradicting factors, are involved and because of deformation of therubber 50. Also the mutually contradicting relationship of sliding andfriction cannot be controlled because of the minituarization of thechip-style electronic component reduces the contact portion. Also as theholes are formed in the silicone rubber 50, it is necessary to payattention to the abrasion of the holes 51 and to discard the rubber 50after certain abrasion.

[0007] The feeding mechanism for feeding the chip-style electroniccomponents into the holding holes 51 of silicone rubber 50 is associatedwith the following drawbacks. For feeding the chip-style electroniccomponents, there is generated employed separation and alignment of thechip-style electronic components by sifting with the insertion guideplate 52 shown in FIG. 11. In this method, as the chip-style electroniccomponents become smaller, the inserting pins 53 also become thinner,thus becoming insufficient in strength and precision. Also the mechanism(jig) becomes inevitably expensive because a high precision is requiredfor the holes of the sifter and those of the holder, and also for therelative positional alignment thereof. In particular, such alignmentwork is extremely difficult.

[0008] Also the conveying mechanism for conveying the chip-styleelectronic components is associated with the following drawbacks.

[0009] The chip-style electronic components having been separated andaligned by the feeding mechanism are held and conveyed by the holes 51of the silicone rubber 50 formed in the form of a plate or a belt. Aplate-shaped holder is conveyed between the process steps eithermanually or by a robot arm. Manual conveying requires a high labor cost,while robot conveying requires a large and expensive equipment. Also abelt-shaped holder can reduce the labor cost and the floor spacerequired for the equipment, but requires a highly precise conveyingmechanism, which inevitably becomes complex and expensive because thealignment is difficult.

[0010] Furthermore, the coating surface of the chip-style electroniccomponent has the following difficulties.

[0011] Prior to the coating with the conductive paste, the coating facesof the chip-style electronic components have to be aligned with a highprecision. Without such alignment work, the dimension B, shown in FIG.10, of a terminal electrode 2 formed on both ends of the chip-styleelectronic component 1, namely the length of the electrode in thelongitudinal direction of the component, shows a significantfluctuation, and the terminal electrode may not be formed in the worstcase.

[0012] On the other hand, the plate-shaped holder is suitable for massproduction because of the large area thereof, but it is difficult toensure planarity. Also the belt-shaped holder is formed with a smallerarea for a smaller size of production, but it is also difficult toensure the position because of the reasons explained in relation to theholding method.

[0013] Furthermore, the coating mechanism for the conductive paste isassociated with the following difficulties.

[0014] A coating mechanism shown in FIG. 14A is to form a uniformconductive paste layer 52 on a flat surface a coating bed 60 by means ofa squeegee 61, while a coating mechanism shown in FIG. 14B is to form auniform conductive paste layer 62, by a squeegee 61, on the peripheralsurface of a coating roller 66 which is immersed in a lower part thereofin a conductive paste reservoir 65. The terminal electrodes are formedby immersing the end portions of the supported chip-style electroniccomponents in the uniform conductive paste layer 62 formed on such flatsurface or on such peripheral surface of the roller.

[0015] In case of the plate-shaped holder, the end portions are immersedin the paste layer formed on a flat surface as shown in FIG. 14A. Alarge area is employed in this method because mass production isintended, and it is difficult to ensure the planarity in such largearea.

[0016] Also in case of the belt-shaped holder, there is generallyemployed the coating roller mechanism shown in FIG. 14B, but it isdifficult to ensure the precision of the center of the roller and thestraightness of the cylindrical surface constituting the roller. Alsothere is required a high precise parallel relationship between the pastelayer and the chip-style electronic components.

[0017] Furthermore, the following difficulties are involved in thedrying the conductive paste applied on the chip-style electroniccomponents.

[0018] The drying of the conductive paste is achieved in an oven using aheater of the electric resistance type, by radiated heat and atmospherictemperature (convection). In order to complete drying by evaporatingsolvent contained in the paste constituting the terminal electrode,there is required a long time under a high temperature (for example 60seconds at 180° C.). In order to withstand such high temperature, theconveying mechanism has to be given a heat-resistant property (forexample metal belt or heat-resistant conveyor). Consequently the designof the conveying system is limited, and such system inevitably involvescomplex mechanisms and control with a high cost. Also there is requireda large floor space for the equipment. Furthermore, even in case theheat-resistant arrangements are adopted, there still result a change inthe conveying position resulting from the thermal dilatation.

[0019] Furthermore, a reversing operation executed for forming theterminal electrodes on both ends of the chip-style electronic componentis associated with the following difficulties.

[0020] In order to form the terminal electrodes on both ends of thechip-style electronic components, it is necessary to position thechip-style electronic components, inserted into the holes 51 of thesilicone rubber 50, by pushing them out to the opposite side with theinserting pins 53. In this operation, it is difficult to ensure exactpositioning and secure operation because of the reasons explained inrelation to the holding method.

[0021] Furthermore, the discharging of the chip-style electroniccomponents after the formation of the terminal electrodes, is associatedwith the following difficulties.

[0022] The chip-style electronic components after the formation of theterminal electrodes are finally pushed out from the holes of thesilicone rubber for example into a receiving box, but, for this purpose,there is again required a complex mechanism for secure discharge.

[0023] Thus, the drawbacks in the conventional terminal electrodeforming method can be listed as follows:

[0024] 1) The terminal electrodes cannot be formed precisely and stablyon miniaturized chip-style electronic component;

[0025] 2) Replacement of the kind of the chip-style electroniccomponents to be processed is time-consuming;

[0026] 3) There are required high costs for the equipment, consumablesand replacement parts;

[0027] 4) The electrode dimension fluctuates significantly since securepositioning (holding) is not achieved at the electrode formingoperation;

[0028] 5) The relative positional (parallel) relationship between theconductive paste layer and the chip holder is unstable, resulting in afluctuation in the dimensional precision of the electrode;

[0029] 6) In the conveying operation in the drying oven, the conveyingmechanism exhibits dimensional change and a loss in the holding abilitybecause of the heat; and

[0030] 7) The long drying time requires a long drying oven, leading to alarger equipment.

SUMMARY OF THE INVENTION

[0031] In consideration of the foregoing, a first object of the presentinvention is to provide a terminal electrode forming method for achip-style electronic component and an apparatus therefor, capable ofadapted to the miniaturization of the chip-style electronic componentand improving the quality of the terminal electrode.

[0032] A second object of the present invention is to provide a terminalelectrode forming method for a chip-style electronic component and anapparatus therefor, capable of reducing the manufacturing cost of thecomponent by simplifying the manufacturing apparatus and reducing thecost thereof, and also enabling mass production of the components ofmany kinds, by significantly reducing the preparation time required forchanging the kind.

[0033] The above-mentioned objects can be attained, according to thepresent invention, by a terminal electrode forming method for achip-style electronic component, comprising:

[0034] an arraying step of arraying chip-style electronic components onan arraying flat bed thereby achieving positioning of the chip-styleelectronic components and aligning the faces thereof;

[0035] an adhering step of lowering a first film coated with an adhesivematerial, together with an adhering top plate parallel to the arrayingflat bed, in relative manner thereby adhering ends of the positioned andaligned chip-style electronic components to the adhesive; and

[0036] a coating step of lowering the aforementioned first film on whichthe chip-style electronic components are adhered together with a coatingtop plate relative to and parallel to a coating flat bed providedthereon with a conductive paste layer of a constant thickness therebypressing the other ends of the chip-style electronic components to thecoating flat bed.

[0037] The above-mentioned terminal electrode forming method for thechip-style electronic component may further comprises:

[0038] a drying step of drying the conductive paste coated on the otherends of the chip-style electronic components in the coating step; and

[0039] a reversing step of positioning, on a reversing bed, a secondfilm coated with an adhesive material, lowering the aforementioned firstfilm holding the chip-style electronic components after the drying step,together with a reversing top plate, in relative manner thereby adheringthe ends, coated with the conductive paste, of the chip-style electroniccomponents to the adhesive of the second film, then peeling off thefirst film togher with the adhesive material thereof, and reversing thesecond film holding the chip-style electronic components.

[0040] There is preferably adopted a configuration in which theaforementioned film is formed as a tape, which is fed from a roll andwound on another roll to convey the chip-style electronic componentssupported by the adhesive material.

[0041] The aforementioned drying step is preferably achieved byconcentrating far-infrared light to the portions, coated with theconductive paste, of the chip-style electronic components.

[0042] There is preferably adopted a configuration in which theaforementioned adhesive is a thermal foaming-release adhesive and thefirst film and the adhesive thereof are peeled off from the chip-styleelectronic components supported by the second by heating of the firstfilm.

[0043] According to the present invention, there is also provided aterminal electrode forming apparatus for a chip-style electroniccomponent, comprising:

[0044] a first tape running mechanism to run a first adhesive tapecoated with an adhesive on a surface thereof;

[0045] a second tape running mechanism to run a second adhesive tapecoated with an adhesive on a surface thereof;

[0046] an electronic component supplying unit to adhere ends of a groupof chip-style electronic components in an arrayed state, on a surface,coated with the adhesive, of the first adhesive tape;

[0047] a first paste applying unit for applying conductive paste bypressing the other ends of a group of the chip-style electroniccomponents, conveyed by running of the first adhesive tape, to a coatingflat bed;

[0048] a first drying unit for drying the conductive paste applied onthe other ends of a group of the chip-style electronic components;

[0049] a transfer unit for transferring a group of the chip-styleelectronic components, after passing the drying unit, from the firstadhesive tape to the second adhesive tape thereby causing the secondadhesisve tape to support the end, coated with the conducted paste, ofthe chip-style electronic components;

[0050] a second paste applying unit for applying conductive paste bypressing the ends, not coated with the conductive paste, of a group ofthe chip-style electronic components, conveyed by running of the secondadhesive tape, to a coating flat bed;

[0051] a second drying unit for drying the conductive paste applied onthe ends of the chip-style electronic components; and

[0052] a discharge unit for peeling a group of the chip-style electroniccomponents from the second adhesive tape.

[0053] In the aforementioned terminal electrode forming apparatus forthe chip-style electronic component, the electronic component supplyunit, the first paste applying unit and the first drying unit providedalong the running path of the first adhesive tape and the second pasteapplying unit and the second drying unit provided along the running pathof the second adhesive tape are preferably provided in a substantiallysame vertical plane and in two steps of different heights.

[0054] It is further preferred that the first adhesive tape receivesadhesion of the chip-style electronic components supplied by theelectronic component supply unit in a state where the surface coatedwith the adhesive is positioned downwards and transfers the chip-styleelectronic components to the first paste coating unit and the firsttdrying unit in a state supporting the chip-style electronic componentsat the lower side, and that the second adhesive tape receives adhesionof the chip-style electronic components in the transfer unit in a statewhere the surface coated with the adhesive positioned downwards andtransfers the chip-style electronic components to the second pastecoating unit and the second drying unit in a state supporting thechip-style electronic components in a state supporting the chip-styleelectronic components at the lower side of the second adhesive tape.

[0055] It is preferred that the adhesives applied on the first andsecond adhesive tapes are thermal foaming-release adhesives and that theforming temperature is higher in the second adhesive tape than in thefirst adhesive tape.

[0056] The electronic component supply unit is preferably provided withan arraying block having a plurality of through holes for housing thechip-style electronic components and capable of arraying the chip-styleelectronic components in a standing state, a reference block having aflat surface for contacting the lower surface of the arraying blockthereby aligning the lower end positions of the chip-style electroniccomponents, and a dropper for dropping the chip-style electroniccomponents into the through holes.

[0057] Furthermore, in dropping the chip-style electronic componentsinto the through holes by the dropper, there is preferably provided agap between the lower surface of the arraying block and the referenceblock in such a manner that the upper ends of the chip-style electroniccomponents do not protrude from the upper surface of the arraying block.

[0058] The first and second tape running mechanisms are preferablyprovided with vacuum suction rollers for respectively driving the firstand second adhesive tapes.

[0059] It is also preferred that each of the first and second pasteapplying units forms, on the coating flat bed, a conductive paste layerfor dipping and a conductive paste layer for blotting or a conductivepaste uncoated surface and is adapted to execute a first operation ofdipping end of a group of the chip-style electronic components into theconductive paste layer for dipping and a second operation of contactingsuch ends with the conductive paste layer for blotting or the conductivepaste uncoated surface thereby returning the excessive conductive pasteto the coating flat bed by blotting.

[0060] It is also preferred that the transfer unit positions the firstadhesive tape at the lower side with the adhesive coated surface thereofon which the chip-style electronic components are adhered upwards andalso positions the second adhesive tape at the upper side with theadhesive coated surface thereof downwards, thereby supporting thechip-style electronic components between the first and second adhesivetapes positioned in parallel manner, and that the chip-style electroniccomponents are supported by the second adhesive tape by dissipating theadhesive property of the first adhesive tape.

[0061] It is furthermore preferred that the running direction of thefirst adhesive tape from the electronic component supply unit to thefirst paste applying unit and the first drying unit and the runningdirection of the second adhesive tape from the transfer unit to thesecond paste applying unit and the second drying unit are mutuallyopposite.

[0062] The present invention is featured by a fact that the chip-styleelectronic components are held by the adhesive material, and thisfeature will be explained further in the following.

[0063] In holding the chip-style electronic components, it is importantnot to perturb the posture thereof.

[0064] Conventionally, in order not to perturb the posture of the heldchip-style electronic components, the holding is achieved by insertioninto rubber holes or by mechanical chucking, so as to withstand thevibrations resulting from the conveying operation or the operations ofprocess steps and the external perturbation (external force) caused byimpact. It is in fact possible to prevent change in the posture bypressing from left and right and from front and back so as to withstandthe external perturbation.

[0065] However, with the progress in the miniaturization of thechip-style electronic components, it is found that the holding executedfor the purpose of preventing the external perturbation may become acause of generating an external perturbation in establising theprecision. For example, the chip-style electronic component insertedinto the rubber hole with a perturbed posture is coated obliquely whensubjected to coating without correction of the posture, or a deficientdimension of the electrode is found because the chip-style electroniccomponent once positioned moves again by the elasticity of rubber.

[0066] In the present invention, an entirely different approach is madeto the aforementioned issue and any holding is eliminated. Such approacheliminates all the factors limiting the increase of precision and allowsto realize highly precise positioning.

[0067] Such approach consists of a method of only adhering an endportion (end face) of the chip-style electronic component and notemploying any other holding means. The chip-style electronic componentadhered by the adhesive has to withstand impacts such as vibrations inthe conveying operation, but complex mechanisms can be dispensed with ifsuch impacts or vibrations can be withstood. In the miniaturizedchip-style electronic component, with its small mass, the momentgenerated by the abrupt acceleration or impact is limited and does notexceed the adhesive force.

[0068] The adhesive material supporting the chip-style electroniccomponent functions as a cushioning material therefor when a vibrationis applied as an external perturbation.

[0069] The adhering method provides following functions:

[0070] holding the chip-style electronic component;

[0071] absoring the fluctuation in the external dimension of thechip-style electronic component;

[0072] absorbing an abnormal shape in the chip-style electroniccomponent;

[0073] memorizing the shape of the absorbed fluctuation or abnormalshape; and

[0074] peelability of the chip-style electronic component.

[0075] The adhesive material, showing jelly-like property, changes itsshape under the application of an excessive displacement, and canmaintain such changed shape though the recovery of the shape occurs byseveral per cent by elasticity. Thus the chip-style electronic componentcan be held and conveyed, maintaining the posture at the attaching byadhesion. Therefore, if the attaching (feeding of the component) isexecuted with a highly precise positioning, such precision can bemaintained thereafter.

[0076] Such holding method is applicable not only to a chip-styleelectronic component with a single terminal at the terminal electrodebut also to a chip-style electronic component with plural terminals atthe terminal electrode.

[0077] Other objects of the present invention, and the features thereof,will become fully apparent from the following detailed description ofthe embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0078]FIG. 1 is a cross-sectional view of a feeding mechanism for achip-style electronic component, representing an embodiment of theterminal electrode forming method of the present invention for thechip-style electronic component;

[0079]FIG. 2 is a plan view of the feeding mechanism;

[0080]FIG. 3 is a schematic view showing a conveying mechanism in anembodiment;

[0081]FIG. 4 is a schematic view showing absorption of the fluctuationof the chip-style electronic components in the embodiment;

[0082]FIG. 5 is a schematic view showing absorption of the abnormalshape in the chip-style electronic components in the embodiment;

[0083]FIG. 6 is a perspective view showing the adhesion and holdiong ofthe chip-style electronic components in the embodiment;

[0084]FIG. 7 is a cross-sectional view of a coating mechanism in anembodiment;

[0085]FIG. 8 is a cross-sectional view of a far-infrared dryingmechanism in an embodiment;

[0086]FIG. 9 is a cross-sectional view showing a reversing mechanism inan embodiment;

[0087]FIG. 10 is a perspective view showing a chip-style electroniccomponent and its terminal electrodes;

[0088]FIG. 11 is a cross-sectional view showing chip supply in aconventional technology;

[0089]FIG. 12 is a perspective view showing a holding method for thechip-style electronic components in a conventional technology;

[0090]FIG. 13 is a cross-sectional view showing such conventionaltechnology;

[0091]FIGS. 14A and 14B are schematic views showing a coating mechanismin a conventional technology;

[0092]FIG. 15 is a schematic view showing a reversing mechanism in aconventional technology;

[0093]FIG. 16 is an elevation view of an embodiment of the terminalelectrode forming apparatus of the present invention for the chip-styleelectronic components;

[0094]FIG. 17 is a lateral cross-sectional view thereof;

[0095]FIG. 18 is a schematic perspective view thereof;

[0096]FIG. 19 is a flow chart of the steps in an embodiment of theapparatus;

[0097]FIGS. 20A and 20B are respectively an elevation view and a lateralcross-sectional view of a drive roller in an embodiment of theapparatus;

[0098]FIG. 21 is a view showing a torque control system for a feedingroll in an embodiment of the apparatus;

[0099]FIG. 22 is a schematic perspective view showing an arrayingcartridge and a dropper in an electronic component supply unit in anembodiment of the apparatus;

[0100]FIGS. 23A and 23B are respectively a plan view and a lateralcross-sectional view of the arraying cartridge;

[0101]FIGS. 24A, 24B, 24C and 24D are views showing principal parts ofthe arraying cartridge;

[0102]FIG. 25 is a schematic perspective view showing the principalconfiguration of a paste coating unit in an embodiment of the apparatus;

[0103]FIGS. 26A, 26B and 26C are respectively an elevation view, across-sectional view and a lateral view of a tape guide in an embodimentof the apparatus;

[0104]FIG. 27 is a lateral cross-sectional view of a drying unit in anembodiment of the apparatus;

[0105]FIGS. 28A and 28B are lateral cross-sectional views of a transferunit in an embodiment of the apparatus; and

[0106]FIG. 29 is a perspective view showing another example of thechip-style electronic component to which the present invention isapplicable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0107] The present invention will be clarified in detail by embodimentsof the terminal electrode forming method for the chip-style electroniccomponent and the apparatus therefor, with reference to the accompanyingdrawings.

[0108] At first there will be explained an embodiment of the terminalelectrode forming method of the present invention for the chip-styleelectronic component, with reference to FIGS. 1 to 9.

[0109]FIGS. 1 and 2 show a supply mechanism for the chip-styleelectronic components. This mechanism arrays the chip-style electroniccomponents on an arraying flat bed 7 utilizing a guide plate 6, therebyachieving an arraying step including positioning of the chip-styleelectronic components and aligning (aligning the height of the lowerends) therefor.

[0110]FIG. 3 shows a PET film 3 of a tape shape coated with a thermalfoaming-release (thermally releasable) adhesive 4. As shown in FIG. 1,the PET film 3 coated with the adhesive 4 is lowered together with anadhering top plate 5 parallel to the arraying flat bed 7 in relativemanner (namely a descent of the top plate 5 or an ascent of the bed 7)to execute an adhering step of adhering ends of the chip-styleelectronic components, already subjected to positioning and alignment,to the adhesive 4. The thermal foaming-release adhesive is also called athermally releasable adhesive, and exhibits a normal adhering force atthe normal temperature but loses the adhering force by the foaming inthe adhesive and by the resulting decrease of the adhering area uponbeing heated to a predetrmined temperature or higher whereby the adheredarticle can be peeled off.

[0111] In the supply mechanism shown in FIGS. 1 and 2, the positioningof the components at the supply thereof is important in attaching thechip-style electronic components 1 on the adhesive 4 of the film 3. Atfirst, on a bed 7 having a highly precise flat surface of a minimumnecessary area for facilitating the mechanical working, a guide plate 6is placed and, into vertical holes 6 a formed therein, the chip-styleelectronic components 1 are vertically dropped. In this operation, theholes 6 a have to be of such a size that the posture of the chip-styleelectronic components 1 can be spontaneously corrected (with a certainplay). The chip-style electronic components 1 are thus arrayed accordingto the planarity of the highly precise flat bed 7. In this state the PETfilm 3 coated with the adhesive 4 is lowered, from above the chip-styleelectronic components, together with the top plate 5 in a highlyprecisely parallel state, whereby the chip-style electronic componentsare held by the adhesive 4 in a state of highly precise positioning.

[0112] As explained in the foregoing, the adhesive 4, showing jelly-likeproperty, changes its shape under application of a displacementexceeding a certain limit, and such changed shape can be approximatelymaintained except for an elastic recovery by several per cent.Therefore, the adhesive 4 is capable, in addition to the holding of thechip-style electronic components 1, of absorbing the fluctuation in theexternal dimension thereof, absorbing the abnormal shape therein, andmemorizing the shape of thus absorbed fluctuation or abnormal shape. Forexample, as shown in FIG. 4, in a state where the chip-style electroniccomponents 1 are held by the adhesive 4 of the film 3, even if there isvariation in length of the chip-style electronic components 1, thecoating faces thereof can be controlled within a range (Rmax in FIG. 4)of 10 μm by the change in the shape of the adhesive 4 and the changedshape memorizing function thereof. Also in case the end portions in apart of the chip-style electronic components 1 have an abnormal shape asshown in FIG. 5 (an inclined top end face), the adhesive 4 becomesrecessed according to such abnormal shape 1 a thereby absorbing thefluctuation resulting from such abnormal shape.

[0113] The chip-style electronic components 1 attached to the tape 3 areheld in the posture-at the attachment and are conveyed to a next step(coating step). The conveying mechanism can be simplified by coating theadhesive 4 on the PET film 3 in the form of a tape, forming such film 3as a roll, feeding the film 3 from a film roll 13A and winding it on afilm roll 13B as shown in FIG. 3.

[0114] As the chip-style electronic components 1 are attached to thefilm 3 in a closely gathered state, there can be processed several tensto several hundreds of the components at a time. Also by such closegathering, any external perturbation perturbing the posture of thechip-style electronic component 1, as indicated by arrows P in FIG. 6,is dispersed among all the chip-style electronic components so that theperturbation of the posture can be effectively prevented.

[0115]FIG. 7 shows a coating mechanism for executing a coating step forapplying conductive paste on the ends of the chip-style electroniccomponents, wherein shown are a coating flat bed 20, and a coating topplate 30 parallel thereto. On the coating flat bed 20 there is providedin advance a conductive paste layer 21 of a constant thickness, by anunrepresented squeegee. The film 3 on which the chip-style electroniccomponents 1 are adhered is lowered together with the coating top plate30 parallel to the coating flat bed 20 in relative manner (namely by adescent of the top plate 30 or by an ascent of the bed 20), whereby theends of the chip-style electronic components 1 are pressed to thecoating flat bed 20 and immersed in the conductive paste layer 21.

[0116] In order to maintain precision in forming the conductive pastelayer 21, the area of the bed 20 has to be made as small as possible. Bypressing the chip-style electronic components 1 to the bed 20 of suchhighly precise flatness, it is rendered possible to absorb theelasticity of the adhesive of several micrometers and to form theelectrodes of high precision.

[0117] After the application of the conductive paste to constituteterminal electrodes 2 on ends of the chip-style electronic components inthe coating step, the components are supplied into a drying mechanismshown in FIG. 8 by the conveying of the film 3, whereupon a drying stepis executed. The drying mechanism is provided with a halogen lamp 35, alight condensing face 36 and a special filter (not shown) for generatingfar-infrared light.

[0118] In the drying step, there is conventionally employed drying byelectric resistance heating. Such drying is achieved by heat conductionbased on convection, by forming an oven structure and elevating thetemperature of the internal atmosphere. Such heating method reauires along time until the completion of drying, thus inevitably extending thelength of the drying oven and expanding the magnitude of the equipment.Also the drying oven requires a heavy heat insulating mechanism, inorder to maintain the temperature of the internal atmosphere.

[0119] On the other hand, the drying mechanism of the present embodimentemploys drying with far infrared light, utilizing the light emitted fromthe halogen lamp 35 instead of heating with an electrical resistor. Thelight emitted from the halogen lamp 35 is transmitted by a specialfilter, thereby being converted into far infrared light IR.

[0120] The wavelength of the far-infrared light is principall 3 μm orlonger. Since the solvent employed in the conductive paste absorbs thelight of a wavelength region of 3 to 6 μm, the paste layer can be heatedfrom the interior within a short time. Also metals do not absorb butreflect such far-infrared light. Utilizing such property, the condensingface 36 composed for example of a metal is used to reflect the emittedlight, thereby simplifying the configuration of the oven and to condensethe reflected light thereby controlling the energy and concentrating thefar-infrared light of a large amount to the portions of the chip-styleelectronic components coated with the conductive paste.

[0121] These factors allow to realize simplification, cost reduction andspace saving of the drying mechanism.

[0122] After the drying step dries the conductive paste coated on theends of the chip-style electronic components, they are supplied, by theconveying of the film 3, to a reversing mechanism shown in FIG. 9, whichexecutes a reversing step of reversing the direction of the chip-styleelectronic components 1 by 180°.

[0123] The reversing mechanism is provided with a reversing flat bed 40and a reversing top plate 41 parallel thereto. On the reversing bed 40,there is provided a PET film 45 (second film) coated with thermalfoaming-release adhesive 46, and the film 3 (first film) holding thechip-style electronic components 1 having been subjected to the dryingstep is lowered together with the reversing top plate 41 in relativemanner (namely by a descent of the top plate 41 or by an ascent of thebed 40) thereby attaching, to the adhesive 46 of the film 45, the endscoated with the conductive paste (to constitute the terminal electrodes2) of the chip-style electronic components 1. Then a releasing heater 42heats the top plate 41 at the side of the film 3 to cause foaming of theadhesive 4 of the first film thereby lowering the adhesive force andreleasing the adhesive 4. Thereafter the film 45 holding the chip-styleelectronic components 1 is reversed by 180°.

[0124] As explained in the foregoing, the PET film 45 coated with theadhesive 46 is adhered to those ends of the chip-style electroniccomponents 1 on which electrodes have already been formed and theadhesive 4 utilized in the preceding step is heated. Then, the adhesive4, consisting of the thermal foaming-release adhesive, loses theadhesive force by heating only, and the chip-style electronic componentscan be easily transferred to the new adhesive 46. In this operation, thereversing bed 40 and the top plate 41 in the opposed position arerequired to have highly precise flatness and highly precise parallelpositioning.

[0125] Instead of the thermal foaming-release adhesives 4, 46, therebymay also be utilized the difference in the adhesive force (or adhesion)in the ordinary adhesives, and, in such case, the latter adhesive 46 isgiven a higher adhesive force.

[0126] The chip-style electronic components 1 held by the film 45 afterthe reversing are subjected to alignment (aligning the height of theupper ends of the chip-style electronic components 1) by the top plate41 from which the film 3 has been removed, and are then subjected tosteps similar to the coating step and the drying step explained inrelation to FIGS. 7 and 8 whereby the terminal electrodes are formed onboth ends of the chip-style electronic components 1.

[0127] The chip-style electronic components after the formation of theterminal electrodes on both ends are released from the film 45 and aredischarged to a receiving box for the chip-style electronic componentsby a discharge mechanism. The adhesive 46 may be composed of a thermalfoaming-release adhesive to achieve such discharge solely by heating,thereby dispensing with a mechanical configuration for the discharge.More specifically, the discharge mechanism can be composed solely of aheat source (far-infrared lamp) for heating the film 45 coated with theadhesive 46 and a receiving box for the discharged chip-style electroniccomponents.

[0128] The present embodiment has the following advantages:

[0129] (1) It can adapt to the miniaturization of the chip-styleelectronic components by coating a film with adhesive and holding thechip-style electronic components with the adhesive. Also owing to theproperty of the adhesive, it can absorb the fluctuation in the externaldimension of the chip-style electronic components and the defectiveshape thereof and can memorize the posture and shape thereof. Also theclose gathering of the chip-style electronic components on the filmallows to disperse the pressure and to improve the stability of theposture of the chip-style electronic components, thereby enabling massproduction and simplification of the attaching and peeling steps.

[0130] (2) The chip-style electronic components can be positioned andaligned with a high precision by arraying the chip-style electroniccomponents on the arraying bed 7 having a highly precise flat surface.

[0131] (3) By forming the PET film 3 coated with the adhesive 4 into atape, there can be realilzed a simple conveying configuration includingroll feeding and roll winding as shown in FIG. 3 (same being applied tothe film 45). Also the conveying configuration utilizing the tape-shapedfilms coated with the thermal foaming-release adhesives realizessimplification of the feeding of the chip-style electronic components,coating of the terminal electrodes, reversing of the components, dryingof the electrodes composed of the coated paste, and the dischargemechanism for the chip-style electronic components.

[0132] (4) The shape memorizing property and the jelly-like property ofthe adhesive coated on the film may be utilized for realizing theabsolute position control with reference to the coating surface. Morespecifically, the adhesive can absorb the fluctuation in the length orthe abnormal shape, eventually present in the chip-style electroniccomponents, as shown in FIGS. 4 and 5, whereby the coating faces thereofcan be aligned.

[0133] (5) The adhesive allows to hold the posture of the chip-styleelectronic components and to eliminate useless external perturbation,and the gathering of the chip-style electronic components enables todisperse the pressure, whereby a high productivity can be realized.

[0134] (6) The coating bed 20 is formed with a smallest possible area toensure a highly precise flatness, thereby ensuring the dimensionalprecision of the thickness of the conductive paste layer 21 formedthereon, and the chip-style electronic components are pressed to thebottom of the paste layer, namely to the highly precise bed 20, wherebythe alignment of the height of the chip-style electronic components canbe realized.

[0135] (7) The chip-style electronic component 1 shown in FIG. 10 forexample has the following dimensions:

[0136] chip component 1005: length L: 1 mm, width W: 0.5 mm, thicknessT: 0.5 mm;

[0137] chip component 0603: length L: 0.6 mm, width W: 0.2 mm, thicknessT: 0.3 mm;

[0138] chip component 0402: length L: 0.4 mm, width W: 0.2 mm, thicknessT: 0.2 mm.

[0139] The above-described holding and highly precise positioning of theminiaturized chip-style electronic components can maintain, for example,in the chip component 0603, a fluctuation of the position of the coatingsurface (Rmax in FIG. 4) within a range of 0.01 to 0.005 mm. Also suchreduced fluctuation of the position of the coating surface of thechip-style electronic components realizes an improvement in theprecision of the electrodes. For example, in the chip component 0603,the precision of the electrodes can be maintained within 0.01 mm(dimension B in FIG. 10). For comparison, in the conventionaltechnology, the dimension B is within 0.02 mm.

[0140] (8) In the drying step, the drying time can be shortened by theirradiation with the far-infrared light. Thus, by employing light energyas the heat source and controlling such heat source, it is possible tosimplify the drying oven and to improve the controllability.

[0141] (9) The reversing mechanism for reversing the chip-styleelectronic components by 180° for forming the terminal electrodes onboth ends of the chip-style electronic component can be realized by asimple mechanism utillizing a mechanism for adhering the PET film 45coated with the adhesive 46 to the chip-style electronic components heldby the thermal foaming-release adhesive 4 of the PET 3, and a peelingmechanism for losing the adhesive force of the thermal foaming-releaseadhesive 4 with heat thereby peeling the film 3.

[0142] (10) The peelability of the thermal foaming-release adhesive 46may be utilized to realize a simple discharging method.

[0143] In the following there will be explained, with reference to FIGS.16 to 29, an embodiment of the terminal electrode forming apparatus forthe chip-style electronic components, for executing the above-describedmeethod.

[0144] FIGS. 16 to 18 are respectively an elevation view, a lateralcross-sectional view and a perspective view showing the entireconfiguration of the terminal electrode forming apparatus for thechip-style electronic components, and FIG. 19 is a view showing theprocess flow, wherein shown are a first tape running mechanism 70 and asecond tape running mechanism 80.

[0145] The first tape running mechanism 70, for a first adhesive tape 71coated with a thermal foaming-release adhesive on a surface thereof, isprovided with a feeding roll 72, a winding roll 73, a driving roller 74and a separator winding roll 75 for winding a separator provided betweenthe layers of the tape. There are also provided guide rollers 76, 77.The drive roller 74 drives the first adhesive tape 74 by a predeterminedamount with vacuum suction of an adhesive-free surface of the firstadhesive tape 71, which is intermittently forwarded by a predeterminedamount by the intermittent rotation of the drive roller 74.

[0146] The second tape running mechanism 80, for a second adhesive tape81 coated with a thermal foaming-release adhesive on a surface thereof,is provided with a feeding roll 82, a winding roll 83, a driving roller84 and a separator winding roll 85 for winding a separator providedbetween the layers of the tape. There are also provided guide rollers86, 87, 88. The drive roller 84 drives the second adhesive tape 84 by apredetermined amount by vacuum suction of an adhesive-free surface ofthe first adhesive tape 81, which is intermittently forwarded by apredetermined amount by the intermittent rotation of the drive roller84.

[0147] Along the running path of the first adhesive tape 71, there areprovided, in succession, an electronic component supply unit 90 foradhering ends of a group of the chip-style electronic components in anarrayed state, to a surface, coated with the adhesive, of the firstadhesive tape 71, a first paste coating unit 100 for coating conductivepaste by pressing, to a coating flat bed, the other ends of the group ofthe chip-style electronic components conveyed by the running of thefirst adhesive tape 71, and a first drying unit 110 for drying theconductive paste coated or applied on the other ends of the group of thechip-style electronic components.

[0148] Also along a portion where the first and second adhesive tapes71, 81 run in parallel, there is provided a transfer unit 120 fortransferring the group of the chip-style electronic components, afterpassing the first drying unit 100, from the first adhesive tape 71 tothe second adhesive tape 81 and causing the group of the chip-styleelectronic components to be held at the ends coated with the conductivepaste.

[0149] Also for processing the group of the chip-style electroniccomponents transferred in the transfer unit 120 to the second adhesivetape 81, there are provided in succession, along the running path of thesecond adhesive tape 81, a leveling unit 130 for aligning the lower endpositions of the group of the chip-style electronic components, a secondpaste coating unit 140 for applying conductive paste by pressing, to acoating flat bed, the ends, not coated with the conductive paste, of thegroup of the chip-style electronic components conveyed by the running ofthe second adhesive tape, and a second drying unit 150 for drying theconductive paste coated on the ends of the group of the chip-styleelectronic components, and a discharge unit 160 for peeling the group ofthe chip-style electronic components from the second adhesive tape 81.

[0150] As shown in FIGS. 16 and 17, these mechanisms are assembled to aframe 171 standing on a base 170.

[0151] The aforementioned first and second adhesive tapes are formed bycoating a surface of a PET film substrate with an adhesive material, andcan be composed, for example, of REVALPHA (trade name) of Nitto DenkoCorporation. The first adhesive tape 71 can be composed of a one-sidecoated tape having a foaming temperature of 150° C. and an adhesiveforce (=adhesive force of adhesive material/tape width) of 3.7 N/20 mm,while the second adhesive tape 71 can be composed of a one-side coatedtape having a foaming temperature of 170° C. and an adhesive force of3.7 N/20 mm. The width of the tapes 71, 81 can be for example 20 mm. Thetape width is selected in consideration of the compactization,simplification and precision assurance of the apparatus. For massproduction not giving emphasis to the precision of the terminalelectrode formation for the chip-style electronic components, a largertape width may be adopted to significantly increase the processingability. The tape has a length of 50 meters per reel, thus capable ofprocessing a million units of the chip-style electronic components in alot. The PET film substrate and the adhesive layer respectively hadthicknesses of 100 μm and 45 μm. However the thickness of the adhesivelayer is preferably about 10% of the dimension L of the chip-styleelectronic component shown in FIG. 10.

[0152] The first and second adhesive tapes 71, 81 may have a sameadhesive force, but, more desirably the first adhesive tape 71 isprovided with a weaker adhesive force (for example 2.4 N/20 mm) forachieving secure transfer in the transfer unit 120.

[0153] A tape having the adhesive on both surfaces of a PET basesubstrate may not be adopted because the posture of the chip-styleelectronic components becomes unstable.

[0154]FIGS. 20A and 20B show a first drive roller 74 for driving thefirst adhesive tape 71 and peripheral mechanisms. As shown in thesedrawings, the first drive roller 74 is composed of a hollow roller body180 and a hollow shaft 181 integral therewith, and the interior of thesecomponents constitute a vacuum chamber 182. On the periphery of thehollow roller body 180, there are formed a plurality of suction holes183 communicating with the vacuum chamber 182, and the interior of thevacuum chamber is evacuated by an evacuating system through a dischargepath 184 to suck the uncoated surface of the first adhesive tape 71thereby driving the same. The hollow shaft 181 is rotatably supported bya bearing 172 on the frame 171. A servo motor 713 for rotating the driveroller 74 is mounted on the frame 171, and the drive roller 74 receivesthe rotary driving force of the servo motor 173 through a pulley 185fixed to the hollow shaft 181.

[0155] A second drive roller 84 for driving the second adhesive tape 81and peripheral mechanisms are constructed in a similar manner as shownin FIGS. 20A and 20B, and will not, therefore, be explained further.

[0156]FIG. 21 shows a mechanism provided around the feed roll 72 formaintaining a constant tension on the first adhesive tape 71. Theremaining amount of the tape on the feeding roll 72 is detected by adisplacement meter 190 (tape reel diameter being measured on real timebasis), and the result of measurement is entered into a controller 191.The controller 191 executes control for maintaining a desired tensionregardless of the remaining tape amount, and sends a control signal toan A/D converter 192. The control signal converted into a digital signalby the A/D converter 192 is processed in a processing device 193, thenconverted back to an analog signal by a D/A converter 194 and is used,through a torque controller 195 for gradually increasing or decreasingthe torque of a tension generating motor 196, whereby a desired constanttension is generated on the first adhesive tape 71 fed from the feedroll 72 which is fixed to the rotary shaft of the motor 196.

[0157] The second adhesive tape 72 is also maintained at a constanttension by a similar mechanism.

[0158]FIG. 22 shows an arraying cartridge 91 and a dropper 92 providedtherearound in the electronic component supply unit 90. The arrayingcartridge 91 is provided, as shown in FIGS. 23A and 23B, with anarraying block 94 having a plurality of through holes 94, serving asarraying holes for the chip-style. electronic components, therebyarraying the components in a standing state, a reference block 95 cominginto contact with the lower surface of the arraying block therebyaligning the lower end positions of the chip-style electroniccomponents, and a holder 96 for integrally holding the arraying block 93and the reference block 95. However, there can be generated a gap ofabout 0.15 mm between the upper surface of the reference block 95 andthe arraying block 93, and, for this purpose, springs 97 are providedbetween the holder 96 and the reference block 95 for biasing thereference block 95 upwards. The reference block 95 preferably has aflatness within 2 μm for the purpose of leveling of the coating surfaceof the chip-style electronic components, and is rendered verticallymovable (within a range of 0.15 mm) from the aforementioned statedistanced from the arraying block 93 to a state in contact therewith.

[0159] The arraying block 91 is designed exclusively for each size ofthe chip-style electronic components, thereby facilitating the change ofthe kind of the component, and also preventing the entry of cracked,chipped or defective ones of the components to the succeeding processsteps.

[0160]FIGS. 24A and 24B are respectively a plan view and a lateralcross-sectional view showing the through holes 94 of the arraying block93 in a magnified scale, while FIG. 24C is a view showing a state inwhich the chip-style electronic components are dropped into the arrayingblock 93 positioned with a gap to the reference block 95, and FIG. 24Dis a view showing a state in which the reference block 95 is maintainedin contact with the lower surface of the arraying block 93 for aligningthe chip-style electronic components. FIGS. 24A to 24D show a preferredexample for a chip-style electronic component of a type 0603 withdimensions L: 0.55 mm, W and T: 0.28 mm shown in FIG. 10. For thedimensions W, T=0.28 mm or a diagonal of 0.42 mm, there is employed athrough hole 94 of a diameter of 0.5 mm. In general, the through hole ispreferably a circular hole of a diameter of about 120% of the chip width(diagonal dimension). Under such setting, the chip-style electroniccomponent 1 stands vertically by self alignment, without the correctionof the posture.

[0161] The upper end of the through hole 94 is rounded and spread in atapered shape.

[0162] Referring to FIG. 22, a dropper 92 around the arraying cartridge91 is composed of a 45° feeder (giving vibration to the chip-styleelectronic components on a vibrating plane in a direction of 45° to ahorizontal plane, and the arraying cartridge 91 vibrates togethertherewith. The dropper 92 drops the chip-style electronic components 1from a vibrating feeder 92A, at the upstream side of the arrayingcartridge 91, to the arraying cartridge 91, thereby causing thechip-style electronic components 1 to fall into the through holes 94serving as the arraying holes formed on the arraying block 93. In moredetail, the chip-style electronic component 1 is thrown forward with anangle of 45° to the horizontal plane, and the landed chip-styleelectronic component enters an arraying hole if an arraying hole ispresent in the landing spot but moves forward if the landing spot isflat. During the dropping operation, since the lower surface of thearraying block 93 is separated from the upper surface of the referenceblock 95 as shown in FIG. 24C, the upper ends of the chip-styleelectronic components do not protrude from the through holes 94.Therefore the chip-style electronic components can smoothly move on thearraying block 93 without meeting any obstacle, and smoothly enter thevacant through holes 94 in successive manner by the repetition of thedropping operation. The chip-style electronic components 1 not enteringthe through holes 94 of the arraying block 93 reach a vibrating feeder92B at the downstream side of the arraying cartridge 91, and arereturned by another returning linear feeder (15° vibration) 98 to thevibrating feeder 92A at the upstream side of the arraying cartridge 91.

[0163] To such arraying cartridge 91 of the electronic component supplyunit 90, there is opposed downwards the adhesive-coated surface of thefirst adhesive tape 71, which is then pressed by the top plate to theupper ends (protruding from the upper surface of the arraying block by0.1 mm) of the group of the chip-style electronic components 1,contained in the through holes 94 of the arraying cartridge 91 andpositioned and aligned by the reference block 95 in the elevatedposition as shown in FIG. 24D, whereby executed is an adhering step ofadhering end of the chip-style electronic components 1 to the adhesivetape 71. In this operation, the press-in amount or penetration of theelectronic components into the adhesive layer of the adhesive tape 71 isselected as about 25 μm in order to obtain a stable supported posture ofthe chip-style electronic components. Such penetration into the adhesiveis desirably about 5% of the dimension L of the chip-style electroniccomponent, or about 50% of the thickness of the adhesive layer.

[0164] Also the rate of density of the group of the chip-styleelectronic components is selected as 638 units/(18×21 mm) in the exampleshown in FIGS. 23A and 23B, in order to generate resistance to theexternal perturbation by such density. Also the chip-style electroniccomponents are arranged with a pitch of 0.8 mm as shown in FIG. 24A,thereby securing a distance for not affecting the electrode formation inthe neighboring chip-style electronic components.

[0165]FIG. 25 shows a conductive paste layer formed on the coating flatbed 101 provided in the first coating unit 100. The coating flat bed 101is positioned parallel to the first adhesive tape 71, and is renderedmovable in a direction perpendicular to the running direction of theadhesive tape 71. On the other hand, a scraping blade 102 for scrapingoff the conductive paste is movable only in the vertical direction.

[0166] For precisely forming the conductive paste layer, the coatingflat bed 101 is preferably formed with an area as small as 30 mm×100 mm,and with a flatness not exceeding 5 μm. Also the parallel level of themovement of the coating flat bed 101 is preferably maintained notexceeding 5 μm. In this manner it is rendered possible to improve theprecision of electrode formation.

[0167] After the entire surface of the coating flat bed 101 is coatedwith the conductive paste, the scraping blade 102 is lowered to a levelsame as that of the upper surface of the coating flat bed 101 and theflat bed is moved by a predetermined amount in a direction P, whereby apaste-free area 101 a is formed on the coating flat bed 101. Then thescraping blade 102 is maintained at a position higher by 0.15 mm thanthe upper surface of the coating flat bed 101 and the coating flat bed101 is moved by a predetermined amount in the direction P, therebyforming a dipping conductive paste layer 103 of a thickness of 0.15 mm.Then the scraping blade 102 is maintained at a position higher by about30 μm than the upper surface of the coating flat bed 101 and the coatingflat bed 101 is moved by a predetermined amount in the direction P,thereby forming a blotting conductive paste layer 104 of a thickness of30 μm.

[0168] In this manner the dipping conductive paste layer 103 and theblotting conductive paste layer 104 are formed in advance. Then thefirst adhesive tape 71 is lowered to immerse (dip), into the dippingconductive paste layer 103, the lower ends of the group of thechip-style electronic components attached to the first adhesive tape 71,thereby forming terminal electrodes on the ends of the chip-styleelectronic components 1 (first operation). After the first adhesive tape71 is returned to the elevated position, the coating flat bed 101 is somoved that the blotting conductive paste layer 104 is opposed to theadhesive tape 71, and the first adhesive tape 71 is lowered to bring thelower ends of the chip-style electronic components 1 in contact with theblotting conductive paste layer 104, thereby returning the excessiveconductive paste on the chip-style electronic components 1 to thecoating flat bed 101 by blotting (second operation). The blottingconductive paste layer 104 is provided in order to facilitate thetransfer of the conductive paste from the chip-style electroniccomponents 1 to the coating flat bed 101 by the mutual contact of theconductive paste layers, and, in principle, there can be utilized ablotting conductive paste layer 104 that has a zero thickness, namely anuncoated surface.

[0169] After each cycle of the dipping and blotting operations for thegroup of the chip-style electronic components, the scraping blade 102 islowered and the coating flat bed 101 is moved to scrape off the usedconductive paste. In this manner it is rendered possible to drasticallyreduce the dropping of the electronic components or the defectiveelectrode formation resulting from contamination with undesirablesubstances.

[0170] The second paste coating unit 140 has a configuration similar tothat of the first paste coating unit 100 explained above.

[0171]FIGS. 26A to 26C illustrate the configuration of a tape guide 200,which is provided at least at the tape winding side and the tape feedingside of the first and second paste coating units 100, 140 for suckingthe uncoated surface of the first and second adhesive tapes 71, 81,thereby preventing skewing or slack feeding of the tapes. As shown inFIGS. 26A to 26C, the tape guide 200 is provided with a guide surface201 on which the adhesive tape 71 or 81 slides and which is providedwith a vacuum suction groove 202 of a square ring shape of a widthsomewhat smaller than the width of the adhesive tape. The vacuum suctiongroove 202 is connected to a vacuum system through a vacuum suction path203 at the back.

[0172]FIG. 27 shows the configuration of the first drying unit 110,which is provided with two sets of a structure having a halogen lamp 112at the center of a light concentrating surface 111. More specifically,in a casing 113 of the drying unit, there are provided a pair ofstructures each containing the halogen lamp 112 at the center of thelight concentrating surface 111, with an irradiating angle of about 40°to 45° to a normal line to the first adhesive tape 71, so as to radiatethe far-infrared light to the paste-coated portions (lower ends) of thechip-style electronic components 1 attached to the first adhesive tape71.

[0173] The irradiating angle of about 40° to 45° is selected becausealso the adhesive tape 71 tends to be heated if the irradiation isexecuted from directly under the chip-style electronic components 1.

[0174] Also in order to suppress the elevation of the atmospherictemperature by the heat from the lamps 112, the casing 113 is enclosedexcept the light transmitting portion and forced air discharge isexecuted by a blower 115 in an exhaust unit 114 connected to the casing113.

[0175] Also the second drying unit 150 has a similar configuration.

[0176]FIG. 28A shows the configuration of the transfer unit 120, inwhich a reference block 121, constituting the upper top plate, issupported and fixed by a frame 171 through a support member 121. Thereference block 122 is provided with a tape holding mechanism by vacuumsuction, in order to hold the second adhesive tape 81.

[0177] On the frame 171, there is also fixed a mounting base 123,holding a slider 124 in vertically slidable manner. The mounting base123 rotatably supports a vertical ball screw shaft 125, which is rotatedby a servo motor 126 fixed to the mounting base 123. The slider 124 isprovided with a ball screw nut 127 engaging with the ball screw shaft125 so that the slider 124 is vertically moved by the rotation of theball screw shaft 125 by the servo motor 126. A hot plate 129constituting a lower flat support plate, parallel and opposed to theflat surface of the aforementioned reference block 122, is fixed to thevertically movable slider 124 through a support member 128.

[0178] As shown in FIG. 28B which is a magnified view seen from alateral direction in FIG. 28A, the reference block 122 and the hot plate129 sandwich the first adhesive tape 71 and the second adhesive tqape 81to adhere the second adhesive tape 81 to the group of the chip-styleelectronic components 1 and to heat the first adhesive tape 71 by thehot plate 129, thereby causing foam generation in the first adhesivetape 71 and lowering the adhesive force thereof (less than 0.15 N/20mm). For example, the first adhesive tape 71 (foaming temperature 150°C.) is heated for 10 seconds at 170° C. by the hot plate in order toexecute foam generation. As the adhesive increases volume at the foamgeneration, the distance of the reference block 122 and the hot plate129 is increased accordingly (about 0.1 mm).

[0179] Thereafter the slider 124 and the hot plate 129 are loweredwhereby the chip-style electronic components 1 supported between thefirst adhesive tape 71 and the second adhesive tape 81 are adhered toand supported by the second adhesive tape 81, and are conveyed togetherwith the second adhesive tape 81 by the rotation of the drive roller 94.

[0180] In the following there will be explained the entire functions ofthe apparatus.

[0181] The first adhesive tape 71 is fed by a predetermined amount bythe drive roller 74, with the adhesive-coated surface downwards, and ispressed by the top plate, in the electronic component supply unit 90shown in FIG. 22, to the upper ends of the group of the chip-styleelectronic components 1 contained in the through holes 94 of thearraying cartridge 90 and positioned and aligned as shown in FIG. 24D.Thus there is executed the adhering step for adhering, to the adhesivetape 71, the ends of the positioned and aligned chip-style electroniccomponents 1.

[0182] After the adhering step, the group of the chip-style electroniccomponents 1 held by the first adhesive tape 71 is transferred to thefirst paste coating unit 100. In this position, the lower ends of thechip-style electronic components 1 are at first dipped in the dippingconductive paste layer 103 on the coating flat bed 101 shown in FIG. 25,and then are brought into contact with the blotting conductive pastelayer 104 by the movement of the coating flat bed 101, whereby theexcessive conductive paste is returned and the electrodes are formedwith the appropriate amount of the conductive paste (coating step).

[0183] After the coating step, the chip-style electronic components 1are transferred, by the running of the first adhesive tape 71, to thefirst drying unit 110 shown in FIG. 27, in which the conductive pasteand the chip-style electronic components are heated to 110° C. to 120°C., while the tape 1 is retained within a range from the ordinarytemperature to about 60° C. For this purpose light irradiation withfar-infrared lamps 112 is employed for heating and is made locally tothe paste-coated portions of the chip-style electronic components fromoblique directions thereunder, thereby only heating the chip-styleelectronic components and the conductive paste and not heating othercomponents.

[0184] After the drying step in the first drying unit 110, the group ofthe chip-style electronic components 1 is reversed by the drive roller74 to a state where the adhesive-coated surface is upwards, and isconveyed to the transfer unit 120 shown in FIGS. 28A and 28B. The firstand second adhesive tapes are sandwiched by the reference block 122 andthe hot plate 129 in such a manner that the first adhesive tape 71 atthe lower side has the adhesive-coated surface upwards while the secondadhesive tape 81 at the upper side has the adhesive-coated surfacedownwards, and the first adhesive tape 71 (foaming at 150° C.) is heatedfor 10 seconds at 170° C. by the hot plate to execute foam generationand to lower the adhesive force thereof. As the adhesive increasesvolume at the foaming, the hot plate 129 has to be retracted accordingly(escaping by lowering of about 0.1 mm). Thereafter the chip-styleelectronic components 1 are attached to the second adhesive tape 81 andare moved by the running motion thereof.

[0185] The group of the chip-style electronic components 1 transferredto the second adhesive tape 81 is transferred to the leveling unit 130,which, not illustrated in detail, corrects the defective posture of thechip-style electronic components and executes alignment of the lowerends of the chip-style electronic components by pressing the lower endsto a reference plane.

[0186] After the alignment in the leveling unit 130, the group of thechip-style electronic components supported by the second adhesive tape81 is conveyed to the second paste coating unit 140 for coating theuncoated ends of the chip-style electronic components with anappropriate amount of the conductive paste in the same manner as in thefirst paste coating unit 100.

[0187] After the coating step, the group of the chip-style electroniccomponents is conveyed by the running motion of the second adhesive tape81 to the second drying unit 150 for executing a drying process similarto that in the first drying unit 110.

[0188] After the drying process in the second drying unit 150, the groupof the chip-style electronic components is transferred to the dischargeunit 160, in which the second adhesive tape 81 (foaming at 170° C.) isheated for 10 seconds at 190° C. by the hot plate, whereby the secondadhesive tape 81 causes foaming and loses the adhesive force. Thus thechip-style electronic components drop by the weight thereof into thedischarge box and are contained therein.

[0189] Annexed Tables 1 to 3 show the dimension and penetration of theadhesive corresponding to each size of the chip-style electroniccomponent, the adhesive forces (or adhesion) of the adhesives to be usedin the first and second adhesive tapes, and the dimension of thearraying holes of the cartridge corresponding to each chip size.

[0190] The foregoing embodiment of the terminal electrode formingapparatus for the chip-style electronic components, explained withreference to FIGS. 16 to 28A and 28B, provides the following advantages:

[0191] (1) On a group of the chip-style electronic components, electrodeformation is executed at first on one ends of such components byconveying the components with the first adhesive tape 71 and by coatingthe conductive paste on such ends, and then on the other ends bytransferring the components to the second adhesive tape 81 and byapplying the conductive paste on such other ends. Thus the terminalelectrode forming steps on both ends of the chip-style electroniccomponents can be automated, with an improvement in the massproducibility.

[0192] (2) The apparatus includes the steps of adhesion of thechip-style electronic components, conductive paste coating, pastedrying, and chip component peeling by the first adhesive tape 71 and thesteps of transfering adhesion of the chip-style electronic components,conductive paste coating, paste drying and chip component peeling by thesecond adhesive tape 81 in a substantially same vertical plane and intwo stages of different levels, thus reducing the required floor areaand achieving space saving.

[0193] (3) The running direction of the first adhesive tape 71 from thefeeding thereof to the adhesion of the chip-style electronic components,coating and drying of the conductive paste is selected opposite to therunning direction of the second adhesive tape 81 from the feedingthereof to the adhesion (transfer) of the chip-style electroniccomponents, coating and drying of the conductive paste, while therunning direction of the first adhesive tape 71 after the reversingthereof to the transfer of the chip-style electronic components isselected same as that of the second adhesive tape 81, whereby the stepsassociated with the first adhesive tape 71 and those associated with thesecond adhesive tape 81 can be positioned within a vertical plane toachieve space saving in the apparatus, and the supply and discharge ofthe chip-style electronic components can be executed in a substantiallysame work site.

[0194] (4) The chip-style electronic components are conveyed to thesteps of conductive paste coating and drying while they are attached tothe downward adhesive-coated surface of the first adhesive tape 71 orthe second adhesive tape 81, and the chip-style electronic componenteventually peeled from the adhesive tape merely drops, so that thedefective components are not mixed into the succeeding steps. Also theterminal electrode formation on the chip-style electronic components isalways executed at the lower side thereof, so that the process matchesthe direction of gravity and allows to maintain a high precision in theelectrode formation.

[0195] (5) In the electronic component supply unit 90, there is employedan arraying cartridge 91 exclusively matching the size of the chip-styleelectronic components, thereby allowing prompt change of the kind of thecomponents. Also a cracked, chipped or abnormal component eventuallypresent is left in the cartridge 91 and is not supplied to thesucceeding step. Also the chip-style electronic components are free fromthe damage, since they are transferred from the arraying cartridge 91 bymerely adhering them to the adhesive tape 71.

[0196] (6) The conductive paste requires a drying time of about 180seconds at 180° C. in the conventional convection drying method.However, the adhesive tape is incapable of holding the chip-styleelectronic components under such conditions because the adhesive losesthe adhesive force by foam formation at about 150° C. In the presentembodiment, such difficulty is avoided by heating the conductive pasteand the chip-style electronic components to 110° C. to 120° C. in thedrying unit 110 or 150 but maintaining the adhesive tape itself within arange from the normal temperature to about 60° C. For this purpose,there is employed heating by light with the far-infrared lamps 112, andthe paste coated portion is locally irradiated with the far-infraredlight from obliquely under the group of the chip-style electroniccomponents, whereby the components and the conductive paste alone arebrought to the desired temperature while other parts are not heated.Irradiation of the group of the chip-style electronic components fromthe vertical direction will require a higher energy because theirradiation is made only to the conductive paste and not to thechip-style electronic components themselves. In such case the adhesivetape will show an increase in temperature, with the resulting foamgeneration, due to an increased energy irradiation to the adhesive tape.Also the increase in the atmospheric temperature by the heat from thelamps 112 is suppressed by employing an enclosed structure which is openonly in the light transmitting portion and discharging heat by theblower 115.

[0197] (7) The chip-style electronic components are fixed in a statesuspending from the first or second adhesive tape. At the transfer fromthe first adhesive tape 71 to the second adhesive tape 81, the firstadhesive tape 71 is reversed so that the chip-style electroniccomponents are positioned upwardly on the first adhesive tape 71.Therefore, the chip-style electronic component failing the transferoperation drops on the first adhesive tape, so that any defectivecomponent is not mixed in the transferred components. Also thecomponents are less susceptible to the external perturbation by gravity,in the electrode formation and in the conveying operation.

[0198] (8) The configuration of the present embodiment allows to realizea chip leveling precision not exceeding 5 μm and a flucgtuation in thedimension B of the chip-style electronic component not exceeding 40 μm.

[0199] The present invention is applicable not only to a single-terminalcomponent shown as the chip-style electronic component in the foregoingembodiment, but also to an array chip 210 having plural terminals at anend as shown in FIG. 29 (a multi-terminal chip-style electroniccomponents). In such case, the pattern of the dipping conductive pastelayer on the paste coating unit has to be adapted to such pluralterminals.

[0200] The present invention has been described by preferred embodimentsthereof, but the present invention is by no means limited by suchembodiments and is subject to various modifications and alterationswithin the scope and spirit of the appended claims.

[0201] As explained in the foregoing, the terminal electrode formingmethod and apparatus of the present invention for the chip-styleelectronic components employs conveying operation by only adhering tothe adhesive, thereby avoiding the drawbacks in the conventonal methodsutilizing silicone rubber holes or mechanical chucks, and thus achievingsimplicity. Also they can be adapted to the miniature-sized chip-styleelectronic components that have been considered impossible to handle inthe conventional method or apparatus. It is furthermore renderedpossible to absorb the fluctuation in the external dimension or theabnormal shape by the deformation of the adhesive, so that the precisionof alignment of the coating surfaces of the chip-style electroniccomponents is drastically improved in comparison with the conventionaltechnology. There can also be expected an improvement in the stabilityof operation of the apparatus and in the production yield.

[0202] Furthermore, the steps can be further simplified by employing athermal foaming-release adhesive as the adhesive material.

[0203] Furthermore, the clarification of the drying mechanism allows toachieve a reduction of the drying time, an improvement in thereliability and a simplification of the apparatus.

[0204] Furthermore, many kinds of the components can be handled in asimple manner with a limited number of interchangeable parts, and themass production is also made possible. TABLE 1 Adhesive dimension andpenetration (mm) Adhesive film thikness Adhesive Penetraton DimensionDimension Dimension (desirable film thickness (desirable PenetrationChip size L W, T B range) (best value) range) (best value) 1005 0.950.48 0.2 0.075 to 0.095 L × 10% 0.035 to 0.045 L × 5% 0603 0.55 0.280.15 0.045 to 0.055 L × 10% 0.020 to 0.030 L × 5% 0402 0.35 0.18 0.10.025 to 0.035 L × 10% 0.015 to 0.020 L × 5%

[0205] TABLE 2 Adhesion Adhesion Adhesion (desirable range) (best value)First tape 2 to 3 N/20 mm 2.4 N/20 mm Second tape 3 to 4 N/20 mm 3.7N/20 mm

[0206] TABLE 3 Arraying hole dimension (mm) Arraying hole Arraying holeChip size (desirable range) (best value) 1005 0.75 mm W, T diagonaldimension × 120% 0603 0.5 mm W, T diagonal dimension × 120% 0402 0.35 mmW, T diagonal dimension × 120%

1-5 (canceled)
 6. A terminal electrode forming apparatus for chip-styleelectronic components comprising: a first tape running mechanism to runa first adhesive tape coated with an adhesive on a surface thereof; asecond tape running mechanism to run a second adhesive tape coated withan adhesive on a surface thereof; an electronic component supply unit toadhere ends of a group of the chip-style electronic components to theadhesive-coated surface of said first adhesive tape in a manner in whichsaid chip-style electronic components are arrayed; a first pasteapplying unit to press the other ends of the group of the chip-styleelectronic components conveyed by the running of said first adhesivetape to a coating flat bed thereby applying conductive paste to theother ends of the group of the chip-style electronic components; a firstdrying unit for drying the conductive paste applied on the other ends ofthe group of the chip-style electronic components; a transfer unit fortransferring the group of the chip-style electronic components havingpassed through said drying unit, from said first adhesive tape to asecond adhesive tape thereby causing the group of the chip-styleelectronic components to be held at the ends coated with the conductivepaste by the second adhesive tape; a second paste applying unit forpressing the ends, not coated with the conductive paste, of the group ofthe chip-style conductive components conveyed by the running of saidsecond adhesive tape to a coating flat bed thereby applying theconductive paste; a second drying unit for drying the conductive pasteapplied on the ends of the group of the chip-style electroniccomponents; and a discharge unit for peeling off the group of thechip-style electronic components from said second adhesive tape.
 7. Aterminal electrode forming apparatus for chip-style electroniccomponents according to claim 6, wherein said electronic componentsupply unit, said first paste applying unit and said first drying unitprovided along the running path of said first adhesive tape and saidsecond paste applying unit and said second drying unit provided alongthe running path of said second adhesive tape are positioned in asubstantially same vertical plane in two stages of different levels. 8.A terminal electrode forming apparatus for chip-style electroniccomponents according to claim 6, wherein said first adhesive tape isadhered, in a state with the adhesive-coated surface thereof downward,to a group of the chip-style electronic components supplied by saidelectronic component supply unit, and conveys the chip-style electroniccomponents at the lower side of said first adhesive tape to said firstpaste applying unit and said first drying unit, and said second adhesivetape is adhered, in a state with the adhesive-coated surface thereofdownward, in said transfer unit to the group of the chip-styleelectronic components and conveys the chip-style electronic componentsat the lower side of said second adhesive tape to said second pasteapplying unit and said second drying unit.
 9. A terminal electrodeforming apparatus for chip-style electronic components according toclaim 6, wherein the adhesives coated on said first and second adhesivetapes are thermal foaming-release adhesives, and the foaming temperatureis selected higher in said second adhesive tape than in said firstadhesive tape.
 10. A terminal electrode forming apparatus for chip-styleelectronic components according to claim 6, wherein said electroniccomponent supply unit is provided with an arraying block having aplurality of through holes for receiving the chip-style electroniccomponents and serving to array the chip-style electronic components ina standing state, a reference block having a flat surface for cominginto contact with the lower surface of said arraying block therebyaligning the lower end levels of the chip-style electronic components,and a dropper for dropping the chip-style electronic components intosaid through holes.
 11. A terminal electrode forming apparatus forchip-style electronic components according to claim 10, wherein a gap isformed between the lower surface of said arraying block and saidreference block when said dropper drops the chip-style electroniccomponents into said through holes, in such a manner that the upper endsof the chip-style electronic components received in said through holesdo not protrude from the upper surface of said arraying block.
 12. Aterminal electrode forming apparatus for chip-style electroniccomponents according to claim 6, wherein said first and second taperunning mechanisms are respectively provided with vacuum suction rollersfor driving the first and second adhesive tapes.
 13. A terminalelectrode forming apparatus for chip-style electronic componentsaccording to claim 6, wherein each of said first and second pasteapplying units forms a conductive paste layer for dipping and aconductive paste layer for blotting or a surface not coated with theconductive paste on said coating flat bed, and is adapted to execute afirst operation for dipping the ends of a group of the chip-styleelectronic components into said dipping conductive paste layer, and asecond operation for contacting said ends with said blotting conductivepaste layer or the conductive paste-uncoated surface thereby returningthe excessive conductive paste to said coating flat bed by blotting. 14.A terminal electrode forming apparatus for chip-style electroniccomponents according to claim 6, wherein said transfer unit holds saidfirst and second adhesive tapes with said group of the chip-styleelectronic components therebetween, by positioning said first adhesivetape at the lower side with the adhesive-coated surface thereof upwardsand said second adhesive tape at the upper side with the adhesive-coatedsurface thereof downwards, and causes said first adhesive tape to losethe adhesive force thereof thereby causing said group of the chip-styleelectronic components to be held by said second adhesive tape.
 15. Aterminal electrode forming apparatus for chip-style electroniccomponents according to claim 6, wherein the running direction of saidfirst adhesive tape through said electronic component supply unit, saidfirst paste applying unit and said first drying unit is opposite to therunning direction of said second adhesive tape through said transferunit, said second paste applying unit and said second drying unit.